1. Symptoms of psychic disorders were found with few exceptions in a series of 205 cases of neoplasm of the brain.2. The mental disorders with brain tumors are essentially similar to those found with other types of organic psychoses and range in severity from mild neuroses to delirium and dementia.3. Four groups are distinguished on the basis of the psychiatric findings.4. The type of clinical picture which develops is influenced by the premorbid personality, by the specific psychic disabilities dependent on regional localization, and by the course and extent of the underlying pathological changes.5. The adjustments of the personality to the psychic problems resulting from the brain tumor are analyzed.6. The need for adequate psychopathological studies as a basis for the localization of mental symptoms is discussed.